22 search results - page 2 / 5 » Bounds on vertex colorings with restrictions on the union of... |
DAM
2007
13 years 7 months ago
2007
In this paper, we prove that the harmonious coloring problem is NP-complete for connected interval and permutation graphs. Given a simple graph G, a harmonious coloring of G is a ...
IWOCA
2009
Springer
14 years 2 months ago
2009
Springer
: We present an improved upper bound of O(d1+ 1 m−1 ) for the (2, F)-subgraph chromatic number χ2,F (G) of any graph G of maximum degree d. Here, m denotes the minimum number of...
ICALP
2011
Springer
12 years 11 months ago
2011
Springer
In [13], Erd˝os et al. defined the local chromatic number of a graph as the minimum number of colors that must appear within distance 1 of a vertex. For any ∆ ≥ 2, there are ...
COMBINATORICS
1999
13 years 7 months ago
1999
An orthogonal coloring of a graph G is a pair {c1, c2} of proper colorings of G, having the property that if two vertices are colored with the same color in c1, then they must hav...
MFCS
2007
Springer
14 years 1 months ago
2007
Springer
We show that every NP problem is polynomially equivalent to a simple combinatorial problem: the membership problem for a special class of digraphs. These classes are defined by me...